1. Field of the Invention
This invention is directed to a composite girder formed from a steel Wide Flange beam with a concrete compression member. A method of forming the composite girder in the field and the apparatus for forming the girder are provided.
2. Description of the Prior Art
Various types of structural beams utilizing combinations of metal and concrete have been proposed in the past. U.S. Pat. No. 1,768,626, French Patent 1,253,986, U.S. Pat. No. 4,416,099 and U.S. Pat. No. 4,495,688 all disclose "I" beams or joists partially enclosed in concrete for various structural purposes. U.S. Pat. No. 2,636,377, U.S. Pat. No. 3,440,793 and U.S. Pat. No. 2,382,138 disclose combinations of "I" beams and concrete reinforcement to strengthen the structural members. U.S. Pat. No. 4,831,800 and U.S. Pat. No. 4,006,523 disclose pre-stressed steel and concrete beams. U.S. Pat. No. 4,493,177 and U.S. Pat. No. 4,369,153 disclose methods and apparatus for forming pre-stressed structural members and concrete panels
None of the foregoing patents discloses a composite girder that is particularly adapted for use in the erection of parking garages. The present invention is directed to such a composite girder which has a concrete cap surrounding the upper flange of a steel Wide Flange beam to serve as a compression member. The concrete compression member attaches itself to the top flange of the Wide Flange beam and the web of the Wide Flange beam. The concrete compression member is at least twice as wide as the Wide Flange beam flange that it encases and has upper surfaces which are perpendicular to the web of the Wide Flange beam but which gradually slope relative to the horizontal surface of the Wide Flange beam flange so that the composite girder may be utilized in combination with other structural members to automatically effect drainage of water from parking garage surfaces.
Because a typical Wide Flange beam of the present invention can be 65 feet long, and the concrete compression member extends the full length of the beam, it is sometime more cost efficient to manufacture the composite girder in the field than to transport it long distances. A method and apparatus have been devised for manufacturing the composite girder in the field.